Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/42—Developers or their precursors
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/30—Imagewise removal using liquid means
  • G03F7/32—Liquid compositions therefor, e.g. developers
  • G03F7/322—Aqueous alkaline compositions

Definitions

• the present invention relates to an aqueous developer solution for positive-working photoresists, based on an aqueous solution of certain basic compounds which have excellent properties with regard to contrast, wall slope and resolution, and a method for development.
• photoresists are used as an auxiliary layer in semiconductor technology.
• Positive-working photoresists are preferably used for this purpose.
• With the aid of the photoresists it is possible to produce relief images which leave the surface to be modified exposed in certain areas and thus make it accessible to further treatment, such as doping or metallization.
• Positive resist images are produced by applying a layer of a photosensitive material to a silicon wafer and then exposing it through a structured mask and selectively dissolving away the exposed parts in the development process.
• Conventional photosensitive compositions are those consisting of alkali-soluble resins, for example of the novolak type, and a photosensitive component, for example an o-quinonediazide.
• alkali-soluble resins for example of the novolak type
• a photosensitive component for example an o-quinonediazide.
• the solubility of the composition in alkaline developers in the exposed parts is dramatically increased by the action of UV light.
• the present invention relates to an aqueous developer solution for positive-working photoresists which contains a water-soluble basic compound, wherein the said compound is a compound of the general formula (I) ##STR2## where R 1 to R 5 are identical or different and are each H, OH, hydroxyalkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms or alkyl of 1 to 4 carbon atoms and x is from 1 to 5.
• This developer solution may additionally contain a nonionic surfactant.
• the novel developer solution contains in general from 5 to 50, preferably from 10 to 40, % by weight, based on the total amount of the developer solution, of a compound of the formula (I).
• Particularly preferred hydroxyalkylpiperidines of the general formula (I) are N-hydroxymethyl-, N-hydroxyethyl-and N-hydroxypropylpiperidine.
• the present invention furthermore relates to a method for developing a positive-working photoresist based on novolak/o-quinonediazide, the resist being applied to a substrate, exposed imagewise and brought into contact with developer solution to form the positive resist image, and the developer solution used being a novel aqueous developer solution, and a method for developing a positive-working photoresist based on poly-(p-hydroxystyrene)/sulfonium salt, a similar process being adopted with the use of the novel developer solution.
• the developer solutions according to the invention have improved stability and development capacity. They therefore make it possible to achieve excellent properties with regard to contrast, wall slope and resolution.
• the novel developer can be used in principle to develop all positive photoresist materials which are essentially based on mixtures of phenolic resins, as the base-soluble matrix, and a photosensitive component.
• Such materials are, for example, the known positive resists based on novolaks and compounds of the naphthoquinonediazide type.
• novolaks in positive resists are given by T. Pampalone in Solid State Technology, June 1984, pages 115-120.
• developer for positive resists based on the systems described in DE-A-37 21 741 and consisting of phenolic polymers and onium salts having acid-labile groups.
• Preferred onium salts are sulfonium salts of the general formula (II) ##STR3## where R 1 to R 3 are identical or different and may each contain aromatic and/or aliphatic radicals which may contain heteroatoms, with the proviso that one or more of the radicals R 1 to R 3 contains an acid-cleavable group, for example a tert-butyl carbonate of a phenol or a silyl ether of a phenol.
• acid-labile groups are preferred, but a large number of other acid-labile groups, such as the known tetrahydropyranyl ethers, ortho esters, trityl and benzyl groups and tert-butyl esters of carboxylic acids, may also be used. It is also possible for two or more sulfonium units in the molecule to be linked via the radicals R 1 to R 3 .
• Preferred counter-ions X.sup. ⁇ are complex metal halides, such as tetrafluoborate, hexafluoroantimonate, hexafluoroarsenate and hexafluorophosphate.
• the phenolic polymers contain, as a rule, units of the general formula (III) ##STR4## where R is hydrogen, halogen or alkyl of 1 to 4 carbon atoms, R 4 , R 5 , R 6 and R 7 are each hydrogen, halogen or alkyl or alkoxy, each of 1 to 4 carbon atoms, R 8 is hydrogen or an acid-labile group, such as trimethylsilyl, tert-butoxycarbonyl, isopropoxycarbonyl or tetrahydropyranyl, and x is from 1 to 3, preferably 1.
• Preferred polymers of the formula (III) are those where R is hydrogen or methyl and R 4 to R 7 are each hydrogen and the radicals R 8 are hydrogen and/or an acid-labile group having one of the abovementioned meanings, --O--R 8 being in the p-position and the proportion of groups where R 8 is hydrogen being not less than 70 mol %.
• These polymers generally have mean molecular weights (M n ) of from 1,000 to 250,000, preferably from 10,000 to 80,000, and are generally present in the radiation-sensitive mixture in an amount of from 40 to 98, preferably from 60 to 95, % by weight.
• Binders having a high aromatic content have the advantage that they are relatively stable in plasma etching processes and reactive ion etching processes.
• the radiation-sensitive mixture may be necessary for the radiation-sensitive mixture to contain both a phenolic polymer based on polyvinylphenol and a novolak of the p-cresol/formaldehyde type, or predominantly o,o'-bonded phenol/formaldehyde, since one of these components alone frequently does not provide all the desired properties.
• novel developer is also suitable for positive resists based on 3-component systems, consisting of an alkali-soluble binder, a compound which forms a strong acid when exposed to actinic radiation and a compound having one or more C--O--C bonds cleavable by an acid, as described in, for example, DE-A-3406927.
• the novel process for producing resist images is carried out in a known manner but with the use of the novel developer.
• the mixtures of phenolic resin and/or phenolic polymer and photosensitive component are generally dissolved in an organic solvent, the solids content being from 5 to 40% by weight.
• Preferred solvents are aliphatic ketones, ethers and esters, and mixtures of these.
• Alkylene glycol monoalkyl ethers for example ethylcellosolve, butyglycol, methylcellosolve and 1-methoxy-2-propanol
• alkylene glycol alkyl ether esters for example methylcellosolve acetate, ethylcellosolve acetate, methylpropylene glycol acetate and ethylpropylene glycol acetate
• ketones for example cyclohexanone, cyclopentanone and methyl ethyl ketone
• acetates such as butyl acetate
• aromatics such as toluene and xylene
• additives such as adhesion promoters, wetting agents, dyes and plasticizers, may also be added.
• sensitizers may, if necessary, also be added in order to sensitize the compounds in the relatively long-wavelength UV to the visible range.
• Polycyclic aromatics such as pyrene and perylene, are preferred, but it is also possible to use other dyes which act as sensitizers.
• the homogeneous solution of the photosensitive mixture can be applied in a conventional manner, for example by spin coating, to the substrate to be coated, in general to a silicon wafer oxidized on the surface, so that a photosensitive layer having a thickness of about 1-2 ⁇ m is obtained, and can be heated at from 60° to 120° C.
• suitable light sources being, for example, high pressure mercury lamps or excimer lasers, a latent image is produced in the photosensitive layer.
• a postexposure bake can, if required, also be carried out, at from 60° to 120° C.
• this postexposure bake is carried out in some cases to reduce the effects due to standing waves; in the case of systems based on poly-(p-hydroxystyrene)/sulfonium salt, however, a postexposure bake at from 60° to 120° C. is essential.
• surfactants it is not necessary to add surfactants to the novel developer solution.
• such substances may be added in general in amounts of not more than 5% by weight, based on the total amount of the developer solution, for example nonylphenoxypoly-(ethyleneoxy)-ethanol, octylphenoxypoly-(ethyleneoxy)-ethanol or commercial fluorinated surfactants.
• the relief produced is dried and then serves as the mask for the further treatment steps, such as etching of the substrate.
• the novel developer has excellent properties with regard to the resolution to be achieved (less than 1 ⁇ m) and wall slope, permits high sensitivity of the resist to short-wavelength UV radiation, has good development capacity and stability and is therefore ideal for microlithography for the production of semiconductor components.
• a commercial positive resist based on novolak/naphthoquinonediazide was applied to surface-oxidized silicon wafers by spin coating, in such a way that, after the wet polymer layer had been dried at 90° C. on a hot plate, 1 ⁇ m thick resist layers resulted.
• the wafers were then exposed in a contact exposure unit through a chromium-coated quartz plate having variable transmission areas and were developed in the downstream development process at 21° C. in 40% strength N-(2-hydroxyethyl)-piperidine solution, the exposed photoresist parts being dissolved. No undesirable residues were detectable on the photoresist images or the exposed developed areas after thorough washing with deionized water.
• Exposure of the coated and predried silicon wafers through the transmission mask was carried out using short-wavelength UV light of wavelength 248 nm, by the contact process under reduced pressure. Following thermal aftertreatment for 1 minute at 100° C., the silicon wafers could be developed in 20% strength N-(2-hydroxyethyl)-piperidine solution of pH 12.4.
• the layer thicknesses were measured using an ⁇ -step profilometer from Tencor.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

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Citations (12)

• 1988
  • 1988-08-13 DE DE3827567A patent/DE3827567A1/de not_active Withdrawn
• 1989
  • 1989-08-09 US US07/391,253 patent/US5039595A/en not_active Ceased
  • 1989-08-10 DE DE89114813T patent/DE58906742D1/de not_active Expired - Lifetime
  • 1989-08-10 CA CA000607987A patent/CA1335338C/en not_active Expired - Fee Related
  • 1989-08-10 EP EP89114813A patent/EP0355015B1/de not_active Expired - Lifetime
  • 1989-08-12 KR KR1019890011596A patent/KR900003676A/ko not_active Application Discontinuation
  • 1989-08-14 JP JP1208029A patent/JPH02103549A/ja active Pending
• 1994
  • 1994-05-09 US US08/240,166 patent/USRE35217E/en not_active Expired - Lifetime

Patent Citations (14)

Non-Patent Citations (5)

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